Effect of Annealing Induced Morphology on Mobility of Copper Phthalocyanine Thin Films

Post deposition annealing of copper phthalocyanine (CuPc) films develops nano-rod structures on the surface of the film and the length and uniformity of nano-rods depend on the annealing temperature. The proposed methodology combines scanning electron microscopy (SEM) and atomic force microscopy (AFM) with impedance spectroscopy to give new insights into the influence of thermally developed nano structures on the charge carrier mobility of CuPc films. The impedance spectroscopy provides a non-invasive and cost-effective study which finds that the hole mobility of CuPc films improves upon increasing annealing temperature, reaches maximum of (5.3 ± 0.7) × 10–5 cm2V−1 s−1 at 150 °C and reduces at higher temperatures. These results will benefit future strategies for the surface modification of small molecular films for improved charge transport in organic and hybrid devices.